A quantum dot (QD), which may also be called a nanocrystal, is a nano particle composed of II-VI group or III-V group elements. The particle size of a quantum dot is generally between 1 and 20 nm, and since electrons and holes are quantum confined, the continuous band structure becomes a discrete energy level structure with molecular properties, and fluorescence may be emitted after the quantum dot is stimulated.
The emission spectrum of a quantum dot may be controlled by changing the size of the quantum dot. By changing the size of a quantum dot and its chemical composition, its emission spectrum can cover the whole visible region. Taking a CdTe quantum dot as an example, when its particle size grows from 2.5 nm to 4.0 nm, the emission wavelength thereof may be red shifted from 510 nm to 660 nm.
Nowadays, with the light emission characteristics of quantum dots, quantum dots may be applied in an organic light emitting diode (OLED) display to achieve full colorization of an OLED, and generally an approach of embossing or transferring is adopted to prepare a quantum dot organic light emitting diode display. However, when the approach of embossing is adopted to prepare a quantum dot organic light emitting diode display, a mold should be designed; red, green and blue quantum dot light emitting layers should be formed by the mold respectively, and it is necessary to process a quantum dot material into ink when in preparation; therefore, the process adopting the approach of embossing is relatively complex; whereas when the approach of transferring is adopted to prepare a quantum dot organic light emitting diode display, the realization of colorization of the display needs transferring for three times; during the transferring, quantum dots are easily left over on a template; and the three colors (red, green, blue) are easy to be mixed; therefore, the adoption of the approach of transferring will lead to a low resolution of the display and it is difficult to realize a batch production.